This invention relates to compatibilizing agents for blends of chlorine containing polymers and carbonyl containing compounds such as polyamide having improved mechanical and thermal properties. The compatibilizing agents are block copolymers of lactones and lactams prepared by sequential bulk polymerization using a mixture of at least one anionic polymerization initiator and optionally at least one co-initiator. Various thermal performance modifiers and impact modifiers can be utilized to improve the thermal properties as well as the impact resistance of a compatibilized blend.
The first studies of the polymerization of lactones were in the 1930s by W. H. Carothers and his coworkers. Subsequently, the mechanisms of cationic, anionic, and coordination polymerization of various lactones were studied throughout the 1950""s to the present. It is well known that polylactones, notably poly(xcex5-caprolactone), of high molecular weight mass exhibit a high compatibility and miscibility with many thermoplastics and elastomeric polymers. Polylactones having melting points lower than polyethylene are thermally stable up to 220xc2x0 C. Above this temperature, they slowly depolymerize to yield lactone monomer and oligomer. Union Carbide, Solvay, and Daicel are commercial producers of a series of polycaprolactones possessing various ranges of molecular weights.
The first commercial polyamides also were developed by W. H. Carothers at the DuPont Company. He obtained many patents on polyamides produced from dicarboxylic acids and diamines. Shortly after DuPont""s entry into the field, I. G. Farbenindustrie obtained patents for polymers based on the ring-opening polymerization of xcex5-caprolactam. Linear aliphatic polyamides, frequently referred to generically as nylons, rank among the most important commercial polymers. They were introduced in the 1930s as the first synthetic fiber, and subsequently as the first crystalline engineering thermoplastic.
Lactone and lactam polymerization caused by a ring-opening process can lead to high molecular weight polymers. Such polymerization of lactones usually has been conducted at relatively low temperatures in an appropriate solvent and at modest rates.
Solvent-free (i.e., bulk) polymerization has been of interest to industry because of its great economic savings. However, one of the problems of bulk polymerization is a difficulty of temperature control caused by exothermic reaction. U.S. Pat. No. 3,021,313 relates to aluminum alkoxides as initiators of the polymerization of monomeric cyclic esters in a conventional reactor. U.S. Pat. No. 3,021,016 relates to metal hydrides as initiators of the polymerization of monomeric cyclic esters in a conventional reactor. The polymers of the patents can be prepared via bulk, suspension, or solution polymerization.
Advantages of the screw extruder as a chemical reactor include fewer processing steps and no need for a solvent. On-line (i.e., in-situ) polymerization, mixing and compounding allow continuous downstream processing, easy devolatilization of by-product, and easy recycling of products. Thus continuous polymerization using a screw extruder (i.e., reactive extrusion) is attractive as an alternative to both bulk and solvent polymerization.
Continuous monomer polymerization of certain urethanes, lactams, acrylates, and styrene using a screw extruder is known in the prior art. Co-rotating and counter-rotating twin screw extruders are considered to be attractive chemical reactors providing good technical and economical means for polymerization and polymer modification.
In particular, continuous polymerization of xcex5-caprolactone in a screw extruder has become possible with alkoxymetallic complexes as initiators that result in short reaction times. U.S. Pat. No. 5,468,837 relates to reactive extrusion of xcex5-caprolactone using aluminum alkoxides. U.S. Pat. No. 5,801,224 relates to reactive extrusion of a cyclic aliphatic ester (e.g. a lactone monomer such as xcex5-caprolactone), optionally together with a secondary component containing hydroxyl or amino group functionality, using coordination insertion catalysts and/or initiators such as Lewis acids and metal alkoxides. The ester must contain less than 100 ppm water and have an acid value less than 0.5 mg KOH/g and preferably less than 0.2 mg KOH/g. It is indicated that higher water and acid content reduces overall polymerization rate and ultimately leads to lower conversion of monomer to polymer. Further, Gimenez et al. reported the reactive extrusion of xcex5-caprolactone catalyzed by tetrapropoxytitanium in Polymer Processing Society 14th Annual Meeting (Yokohama, Japan), PPS-14, pp. 629-630 (1998), and also in International Polymer Processing 15, pp. 20-27 (2000).
U.S. Pat. No. 2,251,519 relates to random polymerization of cyclic amides such as caprolactam, optionally together with cyclic esters such as caprolactone, using any of the alkali or alkali earth metals. However, the reaction was slow, e.g., xc2xd hour to 5 hours. U.S. Pat. No. 3,017,391 relates to faster polymerization of xcex5-caprolactam at lower temperatures using certain nitrogen-containing promoters together with alkali and alkali earth metal catalysts. U.S. Pat. No. 3,200,095 relates to reactive extrusion of 6-caprolactam using a mixture of an alkali metal salt of 6-caprolactam and certain N-substituted compounds free of primary amino groups, such as N-acetyl-6-caprolactam. U.S. Pat. No 3,371,055 relates to reactive extrusion of lactams using a catalyst such as certain alkali or alkali earth metal compounds or certain organometallic compounds of the first to third main group of the Periodic Table, together with certain activators such as acylated lactams and lactams having groups with acylating activity attached to the lactam nitrogen. An article by Kye et al. (Journal of Applied Polymer Science, Vol. 52, pp. 1249-1262 (1994)) relates to reactive anionic polymerization of caprolactam integrated with continuous melt spinning of polyamide-6 fiber.
U.S. Pat. No. 3,758,631 relates to block copolymers prepared by (1) end-capping and optionally chain-extending a polylactone diol with a diisocyanate and (2) thereafter reacting the first step reaction product with caprolactam in the presence of an anionic catalyst for the polymerization of caprolactam. The first step is said to take from about 15 minutes to 3 or 4 hours and the second step from 0.1 to 18 hours. However, the examples show reaction times of hours, making the process impractical for reactive extrusion.
British Patent No. 1,099,184 relates to poly(lactone-lactam)s in which as few as 5 for every 100 units of the polymer chain are amide units. The copolymers are solid crystalline materials having high melting temperature and being substantially insoluble in hydrocarbons. Although the patent states that it includes both random and block copolymers, it is apparent that only random copolymers were envisaged, since each example produced a material with a single, narrow melting point range. The patent also states that the polyesteramides can be blended with other polymers, but there is no teaching as to why or how this might be done.
An article by Goodman et al. (Eur. Polym. J., Vol. 20, No. 3, pp. 241-247 (1984)) relates to copolymers of xcex5-caprolactone and xcfx89-lauryl lactam prepared via anionic polymerization. The products are said to have relatively random structures. However, it is known by those skilled in the art that random xcex5-caprolactone/xcfx89-lauryl lactam copolymers do not work well if at all to compatibilize blending of PVC with other thermoplastics.
An abstract by Ha et al. presented at the Polymer Processing Society""s Aug. 17-19, 1998 meeting in Toronto, Ontario relates to a simultaneous and to a continuous sequential bulk polymerization of lauryl lactam, caprolactone, caprolactam/lauryl lactam, and caprolactone/caprolactam using several anionic catalysts.
New block copolymers are desired that are both relatively easy to prepare, especially via reactive extrusion, as well as suitable for compatibilizing (i.e., facilitating or enhancing) blending of chlorine containing polymers (such as vinyl chloride polymers and the like) with other polymers (such as nylons, maleic anhydride polymers, and the like) in order to produce blends having improved mechanical and thermal properties.
This invention relates to compatibilized blends of chlorine containing polymers and carbonyl containing polymers utilizing high molecular weight block copolymers of lactones and lactams such as xcex5-caprolactone (also known as 6-caprolactone) and xcfx89-lauryl lactam (also known as xcfx89-lauryl lactam) prepared by a sequential bulk polymerization using at least one anionic polymerization initiator and optionally at least one co-initiator block. The block copolymerization of the compatibilizing agent can be performed sequentially in a single reaction vessel by preferably (1) feeding a mixture of xcfx89-lauryl lactam, at least one anionic polymerization initiator, and optionally at least one co-initiator into the vessel and allowing polymerization to occur, and (2) thereafter feeding xcex5-caprolactone into the same vessel and allowing the block copolymer to form. Alternatively, the first step can be performed in one reaction vessel and the reacted contents transferred to a second reaction vessel before addition of xcex5-caprolactone and formation of the block copolymer.
In a preferred embodiment, a single or preferably a twin screw extruder is used as the polymerization reactor in a continuous sequential bulk reactive extrusion process to prepare the poly(xcex5-caprolactone/xcfx89-lauryl lactam) block copolymers of this invention. The continuous reactive extrusion process comprises (1) feeding a mixture of xcfx89-lauryl lactam, at least one anionic polymerization initiator, and at least one co-initiator into the first (i.e., upstream) hopper of a heated, operating extruder, and (2) thereafter feeding xcex5-caprolactone into a second (i.e., downstream) hopper of said extruder.
The invention further relates to utilizing thermal performance modifiers as well as impact modifiers to improve thermal properties such as heat resistance and to improve the impact resistance of the compatibilized blends.
The present invention relates to compatabilized blends of a chloride containing polymer and at least a carbonyl containing polymer. Chlorine containing polymers suitable for use in the present invention are thermoplastics well known to those skilled in the art. The term xe2x80x9cchlorine containing polymersxe2x80x9d includes both polymers derived from chlorine-containing monomers, as well as polymers that are chlorinated during or after polymerization. Examples of such chlorine containing polymers include vinyl chloride homopolymers (PVC), chlorinated PVC (CPVC), polyvinylidene chloride, chlorinated olefins such as chlorinated polyethylene, chlorinated polypropylene, and the like. Other examples include copolymers of vinyl chloride with vinyl acetate; with olefins containing from 2 to about 6 carbon atoms such as ethylene, propylene, chlorinated propylene, butalyene, or, isobutylene; with vinylidene chloride with acrylonitrile; with a conjugated diene having from 4 to 8 carbon atoms such as butadiene; with a vinyl substituted aromatic having from 8 to 12 carbon atoms such as styrene, and the like. Mixtures of such polymers can also be used. Vinyl chloride homopolymers and copolymers are preferred. The amount of such comonomers when utilized is generally from about 5 to about 95 and desirably from about 30 to about 70 percent by weight based upon the total weight of the copolymer. The above polymer or copolymers can contain various additives known to the literature and to the art, such as plasticizers, in conventional amounts.
Examples of thermoplastics carbonyl containing polymers include polyamides (nylons) such as those made from internal amides having a total of from about 4 to about 20 carbon atoms such as polyamide 4 (polybutyrolactam), polyamide 6 (polycaprolactam), polyamide 12 (polylauryl lactam), or polyamides made by the condensation reaction of a diamine monomer having a total of from about 4 to about 15 carbon atoms with a dicarboxylic acid having from about 4 to about 15 carbon atoms such as polyamide 66 (a condensation product of adipic acid and hexamethylenediamine), polyamide 610 (a condensation product of sebacic acid and hexamethylenediamine), polyamide 6-12, polyamide 12-12, and the like with polyamide 12 (polylauryl lactam) being especially preferred. Such polymers can contain conventional additives known to the literature and to the art in conventional amounts.
The amount of the one or more chlorine containing polymers is generally from about 10% or 20% to about 99%, and preferably from about 15%, 35% or 50% to about 90% by weight based upon the total weight of the one or more chlorine containing polymers and the one or more carbonyl containing polymers forming the blend.
The compatibilizing agents relate to block copolymers made from cyclic esters such as lactones having a total of from about 4 to about 10 carbon atoms with about six carbon atoms, i.e. xcex5-caprolactones being preferred. The lactams generally can have a total of from about 8 to about 20 carbon atoms with about 11 or 12 carbon atoms being preferred, for example xcfx89-lauryl lactam.
The compatabilizing agents are generally block copolymers of a lactone and a lactam preferably prepared by sequential bulk polymerization using at least one anionic polymerization initiator and optionally at least one co-initiator. The sequential bulk polymerization generally is a sequential anionic living polymerization in which the lactam such as xcfx89-lauryl lactam monomer is polymerized using the initiator and co-initiator, followed by chemical attachment of the lactone such as xcex5-caprolactone to the propagation chain end of the living poly(lauryl lactam) anion. The block copolymers typically are di-block (AB) copolymers having repeating units such as follows:
xe2x80x94(O(CH2)5CO)xxe2x80x94(NH(CH2)11CO)yxe2x80x94
wherein xe2x80x9cxxe2x80x9d and xe2x80x9cyxe2x80x9d represent the number of units in the respective xe2x80x9cAxe2x80x9d (polymerized xcex5-caprolactone) and xe2x80x9cBxe2x80x9d (polymerized xcfx89-lauryl lactam) blocks. However, other block copolymers also can be produced, such as the ABA tri-block copolymers described below. The amount of xcex5-caprolactone polymerized in the block copolymers of the invention can range from about 1 wt. % to about 80 wt. %. However, for the compatibilizing purposes described herein, the amount of xcex5-caprolactone in said block copolymers can range from about 10 wt. % to about 70 wt. %, preferably from about 20 wt. % to about 65 wt. %, and more preferably from about 25 wt. % or 30 wt. % to about 55 wt. % or 65 wt. %, based upon total weight of the block copolymer. Naturally, the difference is the amount of the one or more lactam blocks.
Suitable initiators for use in this invention are. well known to those skilled in the art and include Group IA (periodic table IUPAC notation, i.e., so-called xe2x80x9calkalinexe2x80x9d) metals, hydrides, and salts, and preferably Group IA metals and hydrides. Lithium, sodium, and potassium metals and hydrides are more preferred, such as Li, Na, K, lithium hydride, sodium hydride, and the like. Other suitable initiators include Group IIA (periodic table IUPAC notation, i.e., so-called xe2x80x9calkaline earthxe2x80x9d) hydrides and salts, and preferably Group IIA hydrides, such as calcium hydride, and the like. Mixtures of initiators can also be used. Typical initiator concentrations can vary from about 1 mmol/mol to about 30 mmol/mol, and preferably from about 4 mmol/mol to about 15 mmol/mol, based on total moles of xcex5-caprolactone and xcfx89-lauryl lactam monomers.
Typically at least one co-initiator is used in an amount of molar concentration in order to keep reaction time of polymerization below about 20 minutes, especially when an extruder is used as the reaction vessel. However, longer reaction times can be suitable in other reaction vessels such as stirred tank reactors, in which case a co-initiator need not be used. The amount of the at least co-initiator is generally from 1 to about 30 and preferably from about 5 to about 20 mmol/mol of total lactam and lactone monomers.
Co-initiators suitable for use in the sequential polymerization include acylated lactam derivatives having the formula: 
as well as Group IA (periodic table IUPAC notation) salts of said derivatives, and mixtures thereof, wherein R and Rxe2x80x2 independently are hydrogen or an alkyl group having from 4 to 10 carbon atoms, preferably 4 to 7 carbon atoms, wherein R and Rxe2x80x2 can join together form an alkylene group in a cyclic structure, and X designates a polar substituent such as an acyl, carbonyl, or cyano group, or the like. Examples of such acylated lactam derivatives are set forth in U.S. Pat. No. 3,200,095, hereby fully incorporated by reference, and include N-acetyl-6-caprolactam, and the like, and mixtures thereof.
Other suitable co-initiators include an isocyanate, such as those having the formula
Rxe2x80x94(NCO)n
wherein R is a hydrocarbon, halohydrocarbon or other generally inert organic group containing carbon atoms, preferably a hydrocarbon group containing from 1 to 10 carbon atoms. The term xe2x80x9cgenerally inertxe2x80x9d refers to organic radicals that do not tend to interfere with the sequential bulk polymerization of this invention. Isocyanates typically are mixtures rather than pure monoisocyanates, diisocyanates, or the like; thus xe2x80x9cnxe2x80x9d in the above formula can be from about 1 to about 3, and preferably is about 2. Use of a monoisocyanate as a co-initiator ideally produces an AB poly(xcex5-caprolactone/xcfx89-lauryl lactam) di-block copolymer. Use of a diisocyanate as a co-initiator ideally produces an ABA tri-block copolymer, which is a caprolactone-lauryl lactam-caprolactone block copolymer.
Examples of suitable diisocyanates include tolylene 2,4- and/or 2,6-diisocyanate, 4,4xe2x80x2-diisocyanato-diphenylmethane, diphenyl-4,4xe2x80x2-diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, xylylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, benzophenone-naphthalene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, 1,4-cyclohexylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,10-decamethylene diisocyanate, and 4,4xe2x80x2-methylene-bis(cyclohexyl isocyanate). 1,6-hexamethylene diisocyanate is preferred. Isocyanate mixtures can also be used.
Sequential bulk polymerization in a single reaction vessel can be performed by a process comprising (1) feeding a lactam such as mixture of xcfx89-lauryl lactam, at least one anionic polymerization initiator, and optionally at least one co-initiator into a single reaction vessel and allowing polymerization to occur, and (2) thereafter feeding a lactone such as xcex5-caprolactone into the same reaction vessel and allowing the block copolymer to form. Alternatively, the first step can be performed in one reaction vessel and the contents transferred to a second reaction vessel before addition of the lactone and formation of the block copolymer. It is preferred that the total amount of initiator and optional co-initiator be added during step (1) of the polymerization, and that no initiator and/or co-initiator be added during step (2) (e.g., not pre-mixed with xcex5-caprolactone) so as to avoid undesirable formation of xcex5-caprolactone oligomers and homopolymers.
In a preferred embodiment, a single or preferably a twin screw extruder is used as the polymerization reactor in a continuous sequential bulk reactive extrusion process to prepare the preferred poly(xcex5-caprolactone/xcfx89-lauryl lactam) block copolymers of this invention. The reactive extrusion process comprises (1) feeding a mixture of xcfx89-lauryl lactam, at least one anionic polymerization initiator, and at least one co-initiator into the first (i.e., upstream) hopper of a heated, operating extruder, and (2) thereafter feeding xcex5-caprolactone into a second (i.e., downstream) hopper of said extruder. The preferred reactive extrusion process of the present invention is substantially solvent free, rapid (typical mean and maximum residence times being no more than about 20 minutes and about 30 minutes respectively), and produces a high conversion of monomers to block copolymer. By the term xe2x80x9csubstantially solvent freexe2x80x9d it is meant that the amount of solvent is generally less than 50% or 25%, desirably less than 15%, and preferably less than 5%, 3%, 2%, or 1% by weight based upon the total weight of the monomers added to form the block copolymer. Said process produces a block copolymer wherein each block (A or B) typically has a number average molecular weight (Mn) from about 5,000 or 10,000 to about 180,000, and more desirably from about 20,000 to 30,000 to about 100,000 or 150,000 (as measured by the method described hereinafter).
Suitable extruders for the process of this invention must accomplish the following functions: (1) mixing the substances introduced (in this case comprising the mixtures of monomers, initiator(s) and co-initiator(s)), (2) conveying the substances as they form a block copolymer from their respective feed zones to a discharge zone such as a die, and (3) maintaining appropriate reaction temperatures. Suitable extruders advantageously will be provided with a degassing vent located near the die. Any known and conventional extruders based on the work of one, two, or a number of screws, whether rotating in the same (co-rotating) or opposite (counter-rotating) directions, are suitable for reactive extrusion to prepare the block copolymers of the invention. The screws can be intermeshing or non-intermeshing (i.e., tangential). Excellent results have been obtained using extruders having two co-rotating, intermeshing screws. Modular twin screw extruders are preferred, i.e., extruders in which screw segments can be assembled (i.e., configured) in customized order in order maximize conversion of monomers to block copolymers. The design of modular screw configurations is well understood by those skilled in the art. Examples of suitable extruders include the Japan Steel Works model TEX-30, which is a 30-mm diameter co-rotating, intermeshing twin screw extruder. Other examples of suitable extruders include the Werner and Pfleiderer model ZSK-30, and the Berstorff model ZE-60. Extruders containing larger screws can also be utilized.
Feed rates to the extruder of monomers, initiators and co-initiators are determined according to the size of the extruder, as well as the desired mean and maximum residence time of reactants in the extruder, according to principles well understood by those skilled in the art. Higher feed rates will result in shorter mean and maximum residence times. Extruder screw speeds can be chosen with consideration of shear level, residence time, and heat generation. For example, a feed rate of about 2 to about 10 kg/hr and a screw speed of about 50 to about 300 rpm are preferred for higher conversion of monomers to block copolymers in a 30-mm diameter screw extruder, such as the Japan Steel Works model TEX-30 and the Werner and Pfleiderer model ZSK-30. Extruder barrel temperature will also affect polymerization rates and can be from about 175xc2x0 C. to about 300xc2x0 C. for the lactam monomer and from about 180xc2x0 C. to about 250xc2x0 C. for the lactone monomer.
The block copolymer can be prepared by feeding the preheated xcex5-caprolactone into the second hopper. It can be preheated from about 25xc2x0 C. to about 200xc2x0 C. in a stirred vessel under a nitrogen atmosphere. A lactam reaction mixture containing the lactam, initiator, and co-initiator is fed into the first (i.e., upstream) hopper of a screw extruder, and subsequently the preheated lactone is fed into a second (i.e., downstream) hopper. It is preferred that the two hoppers be separated by a distance allowing at least about one minute of residence time in the extruder of the first-step materials in order to allow formation of the xcfx89-lauryl lactam xe2x80x9cBxe2x80x9d block portion before addition of xcex5-caprolactone to form the xe2x80x9cAxe2x80x9d block of the block copolymer. The extruder is purged with an inert gas such as nitrogen, argon, etc., during the reactive extrusion process.
The reactive extrusion process produces a yield of at least about 50%, desirably about 60% or 70% and preferably at least about 80%, 90%, or 95% by weight of the block copolymer. Usually, no purification step typically is needed to remove oligomers, homopolymers, and unreacted monomers. The gel permeation chromatography (GPC) test method described hereinafter is used to verify both the molecular weight (MW) and the substantial purity of the block copolymers. After extraction using toluene to ensure removal of polylactone homopolymer, differential scanning calorimetry (DSC) using the test method described hereinafter shows two distinct melting points, indicating production of a block copolymer.
Downstream processing of the block copolymers of the invention can be delayed or can be conducted immediately after the reactive extrusion process. For example, the block copolymers can be cooled, converted into particles, and stored for further processing. Alternatively, the block copolymers can be processed immediately, e.g., by compounding the block copolymers while they are still warm with chlorine containing polymers and optionally other ingredients to form polymer blends having improved mechanical and thermal properties. Processing steps such as pelletizing, film casting, fiber melt spinning, blow molding and injection molding can be integrated into post-reactive extrusion processing. Immediate processing following completion of the reactive extrusion process has the advantage of reducing the thermal history of the final product by eliminating at least one cooling and re-melting step.
The polymers formed from lactams and lactones such as poly(xcex5-caprolactone) homopolymer and poly(xcfx89-lauryl lactam) homopolymer are generally incompatible with one another in their semi-crystalline states. Furthermore, polyamides generally are incompatible with PVC, while poly(xcex5-caprolactone) is miscible with PVC and certain other thermoplastics but does not improve their mechanical and thermal properties. However, the poly(lactone/lactam) block copolymers of the present invention have been found to be good compatibilizing agents for blends of the about noted chlorine containing polymers, and certain other thermoplastics such as polyamides, and also improve the mechanical and thermal properties of the blends.
Additives such as activators, curing agents, stabilizers (such as the Mark series from Witco and the Thermolite series from Elf Atochem), colorants, pigments, plasticizers, waxes, slip and release agents, antimicrobial agents, antioxidants, UV stabilizers, antiozonants, fillers, and the like, can be added optionally during the manufacture of the block copolymers of this invention or during subsequent processing into finished products.
The block copolymers of the present invention can be blended with chlorine containing polymers, other compatible thermoplastics, additives, and other ingredients by techniques well known to those skilled in the art, such as by mixing of ingredients in an electrical heater mixer, Brabender, or screw extruders. The blended ingredients can be mixed further on heated two-roll mills to form a viscous sheet, followed by cooling the sheet in a hot water tank, granulizing or pelletizing the sheet, and packaging the granules or pellets in bags, drums, or boxes for storage and shipment. The pellets or granules subsequently can be processed to form shaped articles, adhesives, and other products.
The amount of the one or more block copolymers of the present invention which are compatibilizing agents for blends of chlorine containing polymers and carbonyl containing polymers is from about 1 to about 20 or 30 parts by weight, and desirably from about 3, 5, or 8 parts to about 12, or 15 parts by weight for every 100 parts by weight of the total weight of the polymers being blended. Such compatibilized polymer blends can be utilized in a wide variety of applications, such as adhesives, wire insulation, tubing, and gaskets. In particular, the block copolymers are useful in compatibilizing (i.e., facilitating or enhancing) the blending of otherwise immiscible or poorly miscible materials (for example, polyamides blended with chlorine containing polymers) in order to produce polymer blends having improved mechanical and thermal properties for such applications. Of course, more than two different types of polymers can be blended so that multiple polymer blends, i.e. containing from 2 to about 5 or 6 polymers, are also within the scope of the present invention.
In order to retain and/or improve thermal properties, such as high heat stability, ultimate tensile strength, elongation at break, and the like, thermal performance modifiers are used. The thermal performance modifiers are often unsaturated anhydride modified polyolefins or polymers made from vinyl substituted aromatic monomers. Suitable polyolefins are generally made from olefin monomers having from 2 to 6 carbon atoms, desirably 2 or 3 carbon atoms with 3 carbon atoms, i.e. propylene being preferred. Suitable vinyl substituted aromatic monomers generally contain from 8 to 12 carbon atoms with 8 or 9 carbon atoms such as styrene or xcex1-methylstyrene being desired. The unsaturated anhydride monomers contain from 4 to 15 carbon atoms, desirably 4 or 5 carbon atoms with maleic anhydride being preferred. The amount of the unsaturated anhydride which is reacted with the olefin or the vinyl substituted aromatic monomers is such that the amount of anhydride is generally from about 0.1, 0.2, 0.3 or 0.5 to about 3, 5, 7, or 10% by weight based upon the total weight of the anhydride modified polymer
The thermal performance modifier preferably also contains a significant amount of a polyolefin homopolymer derived from olefin monomers having from 2 to 6 carbon atoms and thus can be polypropylene or polyethylene, or a homopolymer made from vinyl substituted aromatic monomers having from 8 to 12 carbon atoms and thus can be polystyrene. The amount of such so-called base polymers of the thermal performance modifier can vary greatly but often is from about 10 or 20 to about 60 or 80% by weight based upon the total weight of thermal performance modifier.
When utilized, the amount of the thermal performance modifier is generally from about 5 or 10 to about 40 or 50 parts by weight and preferably from about 15 to about 30 parts by weight for every 100 parts by weight of the blended one or more chlorine containing polymers, one or more carbonyl containing polymers, and the block copolymer.
It is desirable to use various impact modifiers to improve at least the impact resistance of the blend of various chloride containing polymers and carbonyl containing polymers. Suitable impact polymers are often various unsaturated anhydride modified flexible polymers. The unsaturated anhydrides generally have from about 4 to about 15 carbon atoms, desirably 4 or 5 carbon atoms with 4 carbon atoms, for example maleic anhydride being preferred. Flexible polymers include rubber polymers, EPM polymers, that is polymers made from ethylene and propylene monomers; and EPDM polymers, that is polymers made from ethylene, propylene, and a non-conjugated diene monomer. Similar flexible rubbers include ethylene, and other alpha olefins such as butylene and styrene. The amount of non-conjugated diene therein is generally from about 0.1 to about 5% and desirably from about 0.2 to about 4% by weight based upon the total weight of the EPDM.
The unsaturated anhydride is added as a monomer during the polymerization of the various flexible polymers and due to the existence of an unsaturated group therein, reacts with the various flexible polymer forming monomers and generally is located in the backbone of the polymer with the anhydride portion being dependent therefrom. The amount of unsaturated anhydride is generally low, for example, from about 0.1, or 0.2, or 0.3, or 0.5 to about 3, 5, 7, or 10% by weight based upon the total weight of the impact modifier.
The weight of the impact modifier is generally from about 1 to about 50 parts by weight, desirably from about 3 to about 40 and preferably from about 5 to about 30 parts by weight for every 100 parts by weight of the blended one or more per se chlorinated polymers, the one or more per se carbonyl containing polymers such as a polyamide, and the block copolymer.
The mechanism by which the thermal performance and the impact modifiers containing maleic and anhydride work is not fully understood but it is believed that the maleic anhydride portion of the modifier chemically reacts with the amine end group of the polyamide and thus forms a polyamide-g-polymeric modifier which is generally compatible with the polylactam portion of the compatiblizing agent.
The following examples are presented for the purpose of illustrating the invention disclosed herein in greater detail. However, the examples are not to be construed as limiting the invention here in any manner, the scope of the invention being defined by the appended claims.